This invention relates to conveying a recording medium and, more particularly, to varying an amount of force applied to the recording medium by conveying rollers.
Recording media is conveyed using rollers which xe2x80x9cpinchxe2x80x9d the media to move it to/from an imaging location. Heretofore, the same amount of pinch force was applied by the rollers to convey media regardless of the thickness (and thus the stiffness) of the media. This can result in poorly formed images since different amounts of force may be required to accurately convey xe2x80x9cthinxe2x80x9d media (on the order of 0.004 inches thick) than to accurately convey xe2x80x9cthickxe2x80x9d media (on the order of 0.007 to 0.008 inches thick).
In general, in one aspect, the invention features an apparatus which conveys a recording medium. The apparatus includes first and second rollers that define a common area through which the recording medium is conveyed. The first and second rollers contact the recording medium in the common area and rotate in concert to convey the recording medium from the common area. A cam leverages the second roller to vary an amount of nonzero force applied to the recording medium in the common area.
Among the advantages of the invention may be one or more of the following. By leveraging the second roller, it is possible to vary the amount of force applied to the recording medium based, for example, on the thickness of the recording medium. Thus, when used with an imaging apparatus, the invention makes it possible to form accurate images on recording media of different thicknesses.
This aspect of the invention may include one or more of the following features. The common area is defined by surfaces of the first and second rollers. The cam may be movable into plural positions, each of which leverages the second roller differently to change the amount of force. The apparatus may include a bar arranged in a common mechanical coupling with the second roller. The cam is in contact with the bar and is movable relative to the bar to leverage the second roller. The first roller may be a capstan roller and the second roller may be a pinch roller.
The apparatus may include a control mechanism for controlling the cam to leverage the second roller. The control mechanism comprises a first gear connected to the cam, a second gear connected to the first gear by a belt which couples motion of the first gear to the second gear, and a lever which mates to a receptacle in the second gear and which is movable to control motion of the second gear. The second gear may include plural receptacles. The lever is capable of mating to each of these receptacles. The lever controls motion of the second gear to apply a first range of force when mated to a first one of the plural receptacles. The lever controls motion of the second gear to apply a second range of force when mated to a second one of the plural receptacles. The apparatus may include mechanical stops arranged relative to the lever for limiting a range of motion of the lever.
The apparatus may include a member which is in a common mechanical coupling with plural pinch rollers (including the second roller) and a bar which couples to the member and which is in contact with the cam. The cam is rotatable relative to the bar to leverage the plural pinch rollers via the bar and the member. The apparatus may include a second cam on an opposite side of the member from the first cam, and a second bar which couples to the member and which is in contact with the second cam. The second cam is rotatable relative to the second bar to leverage the plural pinch rollers via the second bar and the member.
The apparatus may include a mounting block which is coupled to the second roller, a member which is coupled to the mounting block, and a bar which is coupled to the member and which is in contact with the cam. The cam is rotatable relative to the bar to leverage the second roller via the bar, the member, and the mounting block. The mounting block may include a spring in contact with the member and the second roller for controlling motion of the second roller during leveraging. The apparatus may be part of a laser imaging system.
In general, in another aspect, the invention features an apparatus for conveying a recording medium. The apparatus includes conveying means for conveying the recording medium. The conveying means applies an amount of force to the recording medium during conveying. Changing means changes the amount of force. Among the features that may be included in the invention is a controlling means for controlling the changing means manually.
Other features and advantages of the invention will become apparent from the following description and claims.